TRU COMPONENTS 1.57 inch 4 cm Mini speaker 1 W 8 Ω

Impedance (integer): 8 Ω; Max. frequency: 5000 Hz; Max. load (W): 2 W; Min. frequency: 950 Hz; RMS capacity: 1 W; Recess depth: 11 mm; Recess diameter: 40 mm; Sound pressure: 90 dB; Speaker features: Plastic diaphragm, Damp-proof, Transparent diaphragm; Speaker size (cm): 4 cm; Speaker size (inch): 1.57 inch

Price: £ 3.29 from Conrad Electronic